This invention is generally in the area of drug delivery systems and is particularly related to methods of delivery to the lungs and other components of the pulmonary system.
Many drugs are delivered to the lungs where they are designed to have an effect on the tissue of the lungs, for example, vasodilators or surfactants, or within the bronchi, for example, a bronchodilator, or on a tissue within the lung, for example, a chemotherapeutic agent. Other drugs, especially nucleotide drugs, have been delivered to the lungs because it represents a tissue particularly appropriate for treatment, for example, for genetic therapy in cystic fibrosis, where retroviral vectors expressing a defective adenosine deaminase are administered to the lung. Other drugs which have been used with limited success due to difficulties in administration include vaccines, especially for flu and other respiratory illnesses, where the immune cells of the lung are the target.
Advantages of the lungs for delivery of agents having systemic effects include the large amount of surface area and ease of uptake by the mucosal surface.
It is very difficult to deliver drugs into the lungs. Even systemic delivery has limitations, since this requires administration of high dosages in order to achieve an effective concentration within the lungs.
Most drugs now are administered using a dry powder or aerosol inhaler. These devices are limited in efficacy, however, due to problems in trying to get the drugs past all of the natural barriers, such as the cilia lining the trachea, and in trying to administer a uniform volume and weight of powder.
It is therefore an object of the present invention to provide an improved composition for administration of drugs to the pulmonary system.
It is a further object of the present invention to provide a composition for controlled pulsed or sustained administration of the drugs to the pulmonary system.